Driving condition-monitoring apparatus for automotive vehicles

ABSTRACT

When an automotive vehicle travels to come near one of rest points set in advance (S4), when the abnormality of the driving condition of the driver, or when a continuous driving time period over which the vehicle is continuously driven becomes equal to or longer than a predetermined time period T1, the driver is instructed to take a rest (step S14). When the driver is instructed to take a rest at a point other than the scheduled rest points, a suitable rest point is searched for (S13) to instruct the driver to take a rest there, and subsequent ones of the scheduled rest points are changed (S17).

TECHNICAL FIELD

This invention relates to a driving condition-monitoring apparatus forautomotive vehicles, which instructs the driver to take a rest dependingon the driving condition of an automotive vehicle.

BACKGROUND ART

A long-time driving-warning apparatus for an automotive vehicle isconventionally known which measures a traveling time of the automotivevehicle, and detects a geographical position of the vehicle whenever themeasured traveling time reaches a predetermined time period, to searchthe vicinity of the detected geographical position of the vehicle for aplace where the driver can take a rest, and supply information on theplace to the driver (Japanese Laid-Open Patent Publication (Kokai) No.5-262163).

However, the conventional apparatus does not contemplate cases where thedriver becomes fatigued before the traveling time reaches thepredetermined time period, and therefore there remains room forimprovement.

The present invention has been made in view of the above inconvenience,and it is an object of the invention to provide a drivingcondition-monitoring apparatus for automotive vehicles, which is capableof instructing the driver to take a rest at more suitable timing throughmonitoring the driving condition of the driver.

DISCLOSURE OF THE INVENTION

The present invention provides a driving condition-monitoring apparatusfor an automotive vehicle, shown in FIG. 1, which is comprised ofdriving time-measuring means 1 for measuring a continuous driving timeperiod over which the vehicle is continuously driven, drivingcondition-determining means 2 for determining a driving condition of adriver of the vehicle, rest necessity-determining means 3 fordetermining, based on the continuous driving time period and the drivingcondition of the driver, whether or not it is necessary for the driverto take a rest, map information output means 5 for outputting mapinformation including information on roads on which the automotivevehicle is to travel, vehicle position-detecting means 6 for detecting aposition of the vehicle within the map information, route-setting means7 for setting a driving route to a destination of a drive of thevehicle, scheduled rest point-setting means 8 for setting rest pointsalong the driving route set by the route-setting means at intervals of apredetermined distance and/or a predetermined expected traveling timeperiod, extraordinary rest point search means 4 for searching a place inthe vicinity of the position of the vehicle as an extraordinary restpoint suitable for the driver to take a rest when it is determined thatit is necessary for the driver to take a rest, and rest-instructingmeans 9 for indicating one of the scheduled rest points when the vehiclecomes near the one of the scheduled rest points and indicating theextraordinary rest points when it is determined that it is necessary forthe driver to take a rest.

Wherein, when it is determined that it is necessary for the driver totake a rest and then the driver takes a rest at the rest point newlysearched out by the rest point search means, the rest point-settingmeans 8 changes subsequent ones of the set rest points.

Preferably, the scheduled rest point-setting means 8 changes thesubsequent ones of the scheduled rest points in a manner such that therest points are set at shorter intervals of a distance and/or a timeperiod than the intervals of the predetermined distance and/or thepredetermined expected traveling time.

Preferably, the driving condition-monitoring apparatus includes vehiclespeed-detecting means for detecting a vehicle speed at which theautomotive vehicle is traveling, and wherein the restnecessity-determining means 3 determines whether it is necessary for thedriver to take a rest only when the vehicle speed is equal to or higherthan a predetermined value.

Preferably, the rest-instructing means 9 displays a map including therest points.

Preferably, the rest-instructing means 9 instructs the driver to take arest by using voices or by an indicator.

According to the present invention, it is determined, based on acontinuous driving time period over which the automotive vehicle iscontinuously driven and the driving condition of the driver, whether ornot it is necessary for the driver to take a rest, and if it isdetermined that it is necessary for the driver to take a rest, thedriver is given instructions to take a rest, including information on asuitable rest point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the construction of the invention;

FIG. 2 is a diagram showing the arrangement of a drivingcondition-monitoring apparatus for automotive vehicles, according to anembodiment of the invention;

FIG. 3 is a flowchart showing a routine executed by the FIG. 2 apparatusfor instructing the driver to take a rest;

FIG. 4 is a diagram which is useful in explaining a manner ofinstructing the driver to take a rest;

FIG. 5 is a diagram which is useful in explaining a manner of setting orchanging rest points;

FIG. 6 is a diagram which is useful in explaining another manner ofinstructing the driver to take a rest;

FIG. 7 is a flowchart showing a variation of the FIG. 3 routine;

FIG. 8 is a flowchart showing a routine for determining abnormality ofthe driver; and

FIG. 9 is a timing chart which is useful in explaining the FIG. 8routine.

BEST MODE OF CARRYING OUT THE INVENTION

Next, the invention will now be described in detail with reference todrawings showing a preferred embodiment thereof.

FIG. 2 shows the construction of a driving condition-monitoringapparatus for automotive vehicles, according to an embodiment of theinvention, which is comprised of a control block 10 for controlling theoverall operation of the apparatus, various sensors 11 for detecting thevehicle speed, a yaw rate, etc., and a navigation system 12 of a wellknown type. The navigation system 12 includes a display device fordisplaying a map, etc., and a voice output device comprised of aloudspeaker for giving instructions in voice. The control block 10includes a CPU for carrying out various arithmetic operations, a ROMstoring programs executed by the CPU, a RAM used for execution ofarithmetic operations by the CPU, a timer for measuring a time period,etc., and cooperates with the navigation system 12 to carry out acontrol process, described in detail hereinafter.

According to the present embodiment, the control block 10 forms drivingtime-measuring means 1, part of driving condition-determining means 2,rest necessity-determining means 3, rest point search means 4, restpoint-setting means 8, and part of rest-instructing means 9, and thesensors 11 form part of the driving condition-determining means 2, whilethe navigation system 12 forms map information output means 5, vehicleposition-detecting means 6, route-setting means 7, and part of therest-instructing means 9.

FIG. 3 is a flowchart showing the control process which the controlblock 10 and the navigation system 12 cooperate to carry out.

First, at a step S1, the present position of the automotive vehicle (thevehicle's position) is detected. When the driver inputs destination ofhis drive (at a step S2), a driving route is set (at a step S3). Thesteps S1 to S3 are carried out by the navigation system 12.

At the following step S4, the control block 10 sets scheduled restpoints. Although the scheduled rest points are set along the drivingroute set at the step S3 at intervals of a predetermined distance, thisis not limitative, but they may be set at intervals of a predeterminedexpected traveling time period. Further alternatively, these two mannersof setting the scheduled rest points may be employed in combination suchthat for sections of the driving route which are expected to becongested, scheduled rest points may be set with priority given to thetime-based setting manner, and for the other sections, with prioritygiven to the distance-based setting manner.

At the following step S5, it is determined whether or not the vehicle isbeing driven. The term "being driven" of the vehicle means not only astate in which the vehicle is "traveling" (vehicle speed V>0), but alsoa state in which the vehicle temporarily stops due to congestion or atraffic signal. Therefore, when the ignition switch has been turned off,or when a state of vehicle velocity V=0 has continued over apredetermined time period, it is determined that the vehicle is "notbeing driven". When the vehicle is not being driven, the programproceeds to a step S6, wherein a continuous driving timer TCDRV formeasuring a time period over which the vehicle is continuously driven isreset, followed by terminating the program.

On the other hand, if the vehicle is determined to be driven, the countof the continuous driving timer TCDRV is incremented at a step S7, andthe vehicle's position is detected at a step S8. Then, it is determinedwhether or not the vehicle has come near a scheduled rest point, and ifthe vehicle is determined to have come near a scheduled rest point, theprogram immediately proceeds to a step Sl4.

If the vehicle has not come near a scheduled rest point, it isdetermined at a step S10 whether or not the driving condition of thedriver is abnormal. This determination can be carried out in variousways and will be described hereinafter. If it is determined at the stepS10 that the driving condition of the driver is abnormal, the programimmediately proceeds to a step S12, whereas if it is determined that thedriving condition of the driver is not abnormal, it is determinedwhether or not the vehicle has been driven continuously over apredetermined time period T1 or longer, i.e. the time measured by thecontinuous driving timer TDCRV has become equal to or longer than thepredetermined time period T1. If TCDRV<T1 holds, the program immediatelyproceeds to a step S18, whereas if TDCRV≧T1 holds, the program proceedsto the step S12.

At the step S12, a flag F, which, when set to "1", indicates that thedriving condition of the driver is abnormal or the vehicle has beendriven continuously over the predetermined time period T1 or longer, isset to "1", and then a suitable point for taking a rest which is locatedahead of the vehicle's position is searched for, and sets the nearestsuitable point to a rest point where the driver should take a rest, at astep S13, followed by the program proceeding to a step S14.

At the step S14, instructions for taking a rest are given to the driver.More specifically, the instructions are given by displaying the restpoint 21 (Hasuda Service Area in the illustrated example) on the map aswell as a distance from the vehicle's position to the rest point andtime the vehicle is expected to take to reach there, as shown in FIG. 4.In this figure, reference numeral 22 designates an image indicative ofthe driving route on the map, 23 an image indicative of the vehicle'sposition, and 24 an image indicative of the advancing or travelingdirection. Further, the instructions may be given by lighting anindicator 25 or by voice produced by a voice output device 26.

Referring again to FIG. 3, it is determined at the step S15 whether ornot the driver has actually taken a rest. If the driver has not taken arest, the program returns to the step S14 to instruct the driver to takea rest. If the driver has taken a rest, it is determined whether or notthe flag F assumes "1". If F=0 holds, i.e. if the driver has taken arest at the scheduled rest point, the program immediately returns to thestep S5, whereas if F=1 holds, and hence the driver has taken a restbefore the next scheduled rest point is reached, the subsequentscheduled rest points are changed at a step S17, followed by the programproceeding to the step S18. When the subsequent scheduled rest pointsare changed at the step S17, it is desired that the intervals ofdistance between new rest points are made shorter than the originalintervals of the predetermined distance, since the driver is fatigued.

At the step S18, the flag F is reset to "0", followed by the programreturning to the step S5.

As described above, according to the FIG. 3 control process, if adriving route from a starting point 31 to a destination 32 is set, restpoints (recommended rest points) 35 and 36 are set, as shown in FIG. 5.The illustrated example shows a case where the vehicle is traveling onan express way, and reference numerals 33 and 34 designate interchanges.

If the rest points are not changed during traveling, the driver isinstructed to take a rest at the points 35 and 36, but if the drivingcondition of the driver is detected to be abnormal before the vehiclereaches the point 35, or if the continuous driving time period becomesequal to or longer than the predetermined time period T1, the scheduledrest point 35 is changed to a rest point 35a. In this case, the nextscheduled rest point 36 is also changed to a rest point 36a, and a newrest point 37 is additionally set. The intervals of distance based onwhich the rest points 35a, 36a, and 37 are set shorter than thoseemployed in setting the original scheduled rest points.

As described above, according to the FIG. 3 control process, the driveris instructed to take a rest not only based on the continuous drivingtime period but also based on the driving condition of the driver. As aresult, the driver is instructed to take a rest at more suitable timingdependent on the degree of his fatigue. Further, the instructions fortaking a rest contain information on a rest point found by search, whichreduces the burden on the driver.

In addition to the above-mentioned manners of instructing the driver totake a rest at the step S14, it is also possible to give instructions bylighting a lamp (indicator) built in an instrument panel, not shown, orby producing a voice. Further, there may employed a method asillustrated in FIG. 6, in which a clock of a digital display type anormal operative state of which is indicated by reference numeral 41 maybe caused to repeat a display indicated by reference numeral 42 and adisplay indicated by reference numeral 43 alternately at intervals offive seconds. In the state 42, images of "SA, PA" are displayed, whilein the state 43, the continuous driving time period (2 hours 16 minutesin the illustrated example) is displayed. The driver can cause the clockto return to its normal operative state by pushing a predetermined pushbutton thereof.

Further, the apparatus may be configured such that the driver can set athreshold value (predetermined time period T1) with reference to whichthe driver is instructed to take a rest.

As another variation, as shown in FIG. 7, a step S5a may be interposedbetween the step S5 and S7. That is, according to this variation, it isdetermined whether or not the vehicle speed V is equal to or higher thana predetermined value VLMTL. If V<VLMTL holds, the program proceeds tothe step S5, whereas if V≧VLMTL holds, the program proceeds to the stepS7. This makes it possible to determine whether or not it is necessaryfor the driver has to take a rest only when the vehicle is traveling ata vehicle speed equal to or higher than the predetermined vehicle speed.

Next, the manner of determining the abnormality of the driving conditionof the driver at the step S10 in FIG. 3 will be described with referenceto FIGS. 8 and 9.

FIG. 8 shows a routine for determining abnormality of the drivingcondition of the driver by calculating a reference line or a lane alongwhich the vehicle should travel as well as a parameter (differenceΔDIF1) indicative of a deviation of the vehicle from the reference line,based on a sensed yaw rate YR and the vehicle speed V, and thendetermining the abnormality of the driving condition of the driver basedon the calculated difference ΔDIF1.

First, at a step S21, data of the yaw rate YR and the vehicle speed Vdetected over a predetermined time period T1 (e.g. 30 seconds) beforethe present time are read in whenever a predetermined time period T2(e.g. 10 seconds) elapses. Then, the reference line and a lateraldeviation differential quantity DYK are calculated at steps S22 and S23,respectively.

The reference line and the lateral deviation differential quantity DYKare calculated in the following manner:

First, the input yaw rate YR (FIG. 9(a)) is time-integrated into a yawangle YA (FIG. 9(b)), and further the reference line (indicated by thebroken line in FIG. 9(b)) is calculated, based on the yaw angle YA.Specifically, this calculation is carried out by a least-square method,which is well known, in the following manner:

Let it be assumed, e.g. that yaw angle values YA1, YA2, and YA3 wereobtained at time points t1, t2, and t3, respectively. The reference linecan be approximated by the following linear expressions:

    YA1=b1+b2t1+e1

    YA2=b1+b2t2+e2

    YA3=b1+b2t3+e3

where e1 to e3 represent residuals, and terms b1 and b2 are determinedsuch that the sum of the squares of the residuals e1 to e3 becomes theminimum. The reference line can also be approximated by the followingquadratic expressions:

    YA1=b1+b2t1+b3t1.sup.2 +e1

    YA2=b1+b2t2+b3t2.sup.2 +e2

    YA3=b1+b2t3+b3t3.sup.2 +e3

where terms b1 to b3 are determined such that the sum of the squares ofthe residuals e1 to e3 becomes the minimum.

Further, the reference line can be approximated by the following cubicexpressions:

    YA1=b1+b2t1+b3t1.sup.2 +b4t1.sup.3 +e1

    YA2=b1+b2t2+b3t2.sup.2 +b4t2.sup.3 +e2

    YA3=b1+b2t3+b3t3.sup.2 +b4t3.sup.3 +e3

where terms b1 to b4 are determined such that the sum of the squares ofthe residuals e1 to e3 becomes the minimum.

When the number of sampled data items is larger, higher degreeexpressions are further employed to carry out more accurateapproximation.

In the present embodiment, first, the reference line is determined bythe use of the linear expressions, and then a modified yaw angle YAM(FIG. 9(c)) is calculated by subtracting a reference yaw anglecorresponding to the reference line from the determined yaw angle YA.Further, the lateral deviation differential quantity DYK (FIG. 9(d)) iscalculated by applying the modified yaw angle YAM and the vehicle speedV to the following equation:

    DYK=V×sin(YAM)

Referring again to FIG. 8, at the next step S24, it is determinedwhether or not the difference between the maximum value DYKMAX of thelateral deviation differential quantity DYK and the minimum value DYKMINof the same is smaller than a predetermined value α1. If(DYKMAX-DYKMIN)≧α1 holds, the program returns to the step S22, whereinthe order of approximation of the reference line is increased by oneorder to again calculate the reference line. This procedure isrepeatedly carried out until the answer to the question of the step S24becomes affirmative (YES).

Alternatively, the calculation of the reference line may be terminatedwhen the order of approximation has reached a predetermined value, evenif (DYKMAX-DYKMIN) ≧α1 holds.

If (DYKMAX-DYKMIN)<α1 holds at the step S24, the program proceeds to astep S25, wherein the difference ΔDIF1 is calculated. Then, it isdetermined at a step S26 whether or not the difference ΔDIF1 is equal toor larger than a predetermined reference value ΔDIFLIM1. If ΔDIF124ΔDIFLIM1 holds, it is determined at a step S27 whether or not a winkeris in operation. If ΔDIF1<ΔDIFLIM1 holds or if the winker is inoperation, the program is immediately terminated, whereas ifΔDIF1≧ΔDIFLIM1 holds and at the same time the winker is not inoperation, it is determined that the driving state of the driver isabnormal, followed by terminating the program.

As described above, according to the FIG. 8 routine, it is possible todetermine the abnormality of the driving condition of the driver basedon behavior of the automotive vehicle.

Further, the abnormality of the driving condition of the driver may bedetermined (detected) by executing, e.g. a method of determining a dozeof the driver based on the frequency of operations of the steering wheeland the accelerator pedal as disclosed by Japanese Patent Publication(Kokoku) No. 54-24569, a method of detecting the position of an upperpart of the driver's body by a camera and determining a doze of thedriver based on periodic changes in the detected position of the upperpart of the driver's body as disclosed by Japanese Patent Publication(Kokoku) No. 4-75560, a method of detecting an electric potential on theskin of the driver and detecting a strained state and a loweredawakeness state of the driver based on the detected potential asdisclosed by Japanese Laid-Open Patent Publication (Kokai) No. 5-24460,a method of detecting a doze of the driver based on information on adriver's body, such as an electroencephalogram, a countenance, and bodytemperature as disclosed by Japanese Laid-Open Patent Publication(Kokai) No. 5-96971, and a method of picking up an image of a road infront of the running vehicle by a camera to thereby detect transversedisplacement of the running vehicle, and detecting a doze of the driverbased on the detected transverse displacement as disclosed in JapaneseLaid-Open Patent Publication (Kokai) No. 5-69757, etc. In short, theabnormality of the driving condition of the driver may be determined notonly based on the behavior of the vehicle, but also based on drivingoperations, or states or conditions (posture, body temperature, etc.) ofthe driver.

Industrial Applicability

As described in detail heretofore, according to the present invention,it is determined whether or not it is necessary for the driver to take arest, based on a continuous driving time period over which the vehicleis continuously driven and the driving condition of the driver, and whenit is determined that it is necessary for the driver to take a rest, thedriver is instructed to take a rest. Therefore, it is possible toinstruct the driver to take a rest at more suitable timing in a mannerdependent on a degree of his fatigue. Further, the instructions fortaking a rest contains information on a rest point found by search,which reduces the burden on the driver.

We claim:
 1. A driving condition-monitoring apparatus for an automotivevehicle, comprising driving time-measuring means for measuring acontinuous driving time period over which said vehicle is continuouslydriven, driving condition-determining means for determining a drivingcondition of a driver of said vehicle, rest necessity-determining meansfor determining, based on said continuous driving time period and saiddriving condition of said driver, whether or not it is necessary for thedriver to take a rest, map information output means for outputting mapinformation including information on roads on which said automotivevehicle is to travel, vehicle position-detecting means for detecting aposition of said vehicle within said map information, route-settingmeans for setting a driving route to a destination of a drive of saidvehicle, scheduled rest point-setting means for setting rest pointsalong said driving route set by said route-setting means at intervals ofa predetermined distance and/or a predetermined expected traveling timeperiod, extraordinary rest point search means for searching a place inthe vicinity of said position of said vehicle as a rest point suitablefor said driver to take a rest when it is determined that it isnecessary for said driver to take a rest, and rest-instructing means forindicating one of said scheduled rest points when said vehicle comesnear said one of said scheduled rest points and indicating saidextraordinary rest point when it is determined that it is necessary forsaid driver to take a rest, wherein when it is determined that it isnecessary for said driver to take a rest and then said driver takes arest at said extraordinary rest point newly searched out by said restpoint search means, said scheduled rest point-setting means changessubsequent ones of said scheduled rest points.
 2. A drivingcondition-monitoring apparatus according to claim 1, wherein saidscheduled rest point-setting means changes said subsequent ones of thescheduled rest points in a manner such that the rest points are set atshorter intervals of a distance and/or a time period than said intervalsof said predetermined distance and/or said predetermined expectedtraveling time.
 3. A driving condition-monitoring apparatus according toclaim 1, including vehicle speed-detecting means for detecting a vehiclespeed at which said automotive vehicle is traveling, and wherein saidrest necessity-determining means determines whether it is necessary forsaid driver to take a rest only when said vehicle speed is equal to orhigher than a predetermined value.
 4. A driving condition-monitoringapparatus according to claim 1, wherein said rest-instructing meansdisplays a map including said rest points.
 5. A drivingcondition-monitoring apparatus according to claim 4, wherein saidrest-instructing means instructs said driver to take a rest by usingvoices or by an indicator.